9pnet_virtio: no channels available for device syz
netlink: 24 bytes leftover after parsing attributes in process `syz.5.933'.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.5.933/8112 is trying to acquire lock:
ffff888073144478 (&hdev->lock){+.+.}-{3:3}, at: sco_sock_connect+0x189/0x940 net/bluetooth/sco.c:608

but task is already holding lock:
ffff88805fbc3120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1744 [inline]
ffff88805fbc3120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_sock_connect+0xa7/0x940 net/bluetooth/sco.c:592

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}:
       lock_sock_nested+0x44/0x100 net/core/sock.c:3258
       lock_sock include/net/sock.h:1744 [inline]
       sco_conn_ready net/bluetooth/sco.c:1155 [inline]
       sco_connect_cfm+0x70a/0xd00 net/bluetooth/sco.c:1232
       hci_connect_cfm include/net/bluetooth/hci_core.h:1507 [inline]
       hci_sync_conn_complete_evt+0x4be/0x9d0 net/bluetooth/hci_event.c:4576
       hci_event_packet+0x8cf/0x1310 net/bluetooth/hci_event.c:6517
       hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5190
       process_one_work+0x867/0xff0 kernel/workqueue.c:2310
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #1 (hci_cb_list_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       hci_connect_cfm include/net/bluetooth/hci_core.h:1504 [inline]
       hci_remote_features_evt+0x5d9/0xa10 net/bluetooth/hci_event.c:3367
       hci_event_packet+0x600/0x1310 net/bluetooth/hci_event.c:6455
       hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5190
       process_one_work+0x867/0xff0 kernel/workqueue.c:2310
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #0 (&hdev->lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       sco_sock_connect+0x189/0x940 net/bluetooth/sco.c:608
       __sys_connect_file net/socket.c:1933 [inline]
       __sys_connect+0x3cb/0x450 net/socket.c:1950
       __do_sys_connect net/socket.c:1960 [inline]
       __se_sys_connect net/socket.c:1957 [inline]
       __x64_sys_connect+0x76/0x80 net/socket.c:1957
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  &hdev->lock --> hci_cb_list_lock --> sk_lock-AF_BLUETOOTH-BTPROTO_SCO

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sk_lock-AF_BLUETOOTH-BTPROTO_SCO);
                               lock(hci_cb_list_lock);
                               lock(sk_lock-AF_BLUETOOTH-BTPROTO_SCO);
  lock(&hdev->lock);

 *** DEADLOCK ***

1 lock held by syz.5.933/8112:
 #0: ffff88805fbc3120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1744 [inline]
 #0: ffff88805fbc3120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_sock_connect+0xa7/0x940 net/bluetooth/sco.c:592

stack backtrace:
CPU: 1 PID: 8112 Comm: syz.5.933 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625
 __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 sco_sock_connect+0x189/0x940 net/bluetooth/sco.c:608
 __sys_connect_file net/socket.c:1933 [inline]
 __sys_connect+0x3cb/0x450 net/socket.c:1950
 __do_sys_connect net/socket.c:1960 [inline]
 __se_sys_connect net/socket.c:1957 [inline]
 __x64_sys_connect+0x76/0x80 net/socket.c:1957
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f2fc87a9159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2fc69e0028 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f2fc8a31090 RCX: 00007f2fc87a9159
RDX: 0000000000000008 RSI: 0000200000000100 RDI: 000000000000000a
RBP: 00007f2fc884006b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2fc8a31128 R14: 00007f2fc8a31090 R15: 00007ffc2870af58
 </TASK>